Ilia Alshanetsky has started to gather more and more information about PHP usage on the web as a whole (that was started here) and has been extended with some additional statistics he's done on the location of the domains he's collected.

The first step of the process has been resolving all of these domains, which is now complete. The next step is fetching the server information, which began, but will take some time to finish. However, even from the domain revolving data there is a lot of useful data to be gleamed, which is what I am now publishing. My first focus was on the world-wide distribution on these TLDs, which at least for me held a few surprises.

He includes a few graphs of the results he's found showing things like:

The US has the most domains hosted followed with less than half by Germany

The overwhelming majority of the PHP domains are in the .com area

In the US, the state with the highest number of PHP-powered domains was Arizona with Clifornia coming in second

If you'd like something more interactive, he's also come up with a clickable world map of the results for you to click around on.